Drug used in asthma Notes PDF

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Drugs Used in Asthma Notes: Downloadable PDF

Download comprehensive notes on drugs used in the treatment of asthma in PDF format. These notes cover the various classes of medications used to manage asthma, including bronchodilators (beta2-agonists, anticholinergics), inhaled and systemic corticosteroids, leukotriene modifiers, mast cell stabilizers, anti-IgE monoclonal antibodies, and methylxanthines (theophylline). Learn about their mechanisms of action, clinical uses, benefits, and potential side effects. Includes information on both quick-relief and long-term control medications. Ideal for students, researchers, and healthcare professionals. Download now for convenient offline access.

Keywords: Asthma, Drugs, Medications, PDF, Download, Notes, Bronchodilators, Beta2-Agonists, Anticholinergics, Inhaled Corticosteroids, Systemic Corticosteroids, Leukotriene Modifiers, Mast Cell Stabilizers, Anti-IgE, Omalizumab, Theophylline, Methylxanthines, Pharmacology, Respiratory, Mechanism of Action, Clinical Uses, Side Effects, Quick-Relief Medications, Long-Term Control Medications, SABA, LABA, ICS, LTRA.

Drugs Used in the Treatment of Asthma: Mechanisms and Management

Asthma is a chronic inflammatory disease of the airways characterized by airway hyperresponsiveness, bronchoconstriction (narrowing of the airways), and inflammation. The goals of asthma treatment are to control symptoms, prevent exacerbations (asthma attacks), maintain normal lung function, and minimize the risk of long-term complications. Medications play a crucial role in achieving these goals. This document provides an overview of drugs used in asthma.

Pathophysiology of Asthma (Brief Overview)

Asthma involves a complex interplay of factors, including:

• Airway Inflammation: Chronic inflammation of the airways, involving various inflammatory cells (e.g., eosinophils, mast cells, T lymphocytes) and mediators (e.g., histamine, leukotrienes, cytokines).
• Airway Hyperresponsiveness: Increased sensitivity of the airways to various stimuli (e.g., allergens, irritants, cold air, exercise), leading to bronchoconstriction.
• Bronchoconstriction: Contraction of the smooth muscle surrounding the airways, narrowing the airways and making it difficult to breathe.
• Airway Remodeling: Long-term changes in the structure of the airways, including increased smooth muscle mass, mucus hypersecretion, and subepithelial fibrosis.

Drug Classes Used in Asthma

Asthma medications are broadly classified into two categories: quick-relief medications (used to treat acute symptoms) and long-term control medications (used to prevent symptoms and reduce airway inflammation).

• Bronchodilators: Relax the smooth muscle around the airways, opening them up and making it easier to breathe.
  • Beta2-Adrenergic Agonists (Beta2-Agonists):
    • Short-Acting Beta2-Agonists (SABAs):
      • Examples: Albuterol (salbutamol), Levalbuterol, Terbutaline.
      • Mechanism of Action: Stimulate beta2-adrenergic receptors on airway smooth muscle, leading to an increase in cyclic AMP (cAMP) and relaxation of the muscle.
      • Clinical Uses: Quick-relief medication for acute asthma symptoms (wheezing, shortness of breath, chest tightness). Used as "rescue inhalers."
      • Side effects: Tachycardia.
    • Long-Acting Beta2-Agonists (LABAs):
      • Examples: Salmeterol, Formoterol, Arformoterol, Indacaterol, Olodaterol, Vilanterol.
      • Mechanism of Action: Similar to SABAs, but with a longer duration of action (12 hours or longer).
      • Clinical Uses: Long-term control medication, used in combination with inhaled corticosteroids (ICS) to prevent asthma symptoms and exacerbations. *LABAs should never be used alone for asthma treatment due to an increased risk of asthma-related death.*
      • Side effects: Tachycardia.
  • Anticholinergics (Muscarinic Antagonists):
    • Short-Acting Muscarinic Antagonists (SAMAs):
      • Example: Ipratropium bromide.
    • Long-Acting Muscarinic Antagonists (LAMAs):
      • Example: Tiotropium, Aclidinium, Glycopyrrolate, Umeclidinium.
    • Mechanism of Action: Block the action of acetylcholine at muscarinic receptors on airway smooth muscle, preventing bronchoconstriction.
    • Clinical Uses: Can be used as an add-on therapy to SABAs in acute asthma exacerbations. More commonly used in COPD.
    • Side Effects: Dry mouth.
  • Methylxanthines:
    • Examples: Theophylline.
    • Mechanism of Action: A phosphodiesterase inhibitor.
    • Side effects: It has narrow therapeutic window.
• Anti-inflammatory Drugs: Reduce airway inflammation, the underlying cause of asthma.
  • Inhaled Corticosteroids (ICS):
    • Examples: Beclomethasone, Budesonide, Fluticasone, Mometasone, Ciclesonide.
    • Mechanism of Action: Reduce airway inflammation by decreasing the production of inflammatory mediators and reducing the activity of inflammatory cells. ICS are the most effective long-term control medications for asthma.
    • Clinical Uses: Long-term control medication for persistent asthma. Used to prevent symptoms, reduce exacerbations, and improve lung function.
    • Side Effects: Oral candidiasis (thrush), hoarseness, cough. Systemic side effects are rare with inhaled corticosteroids at recommended doses.
  • Systemic Corticosteroids:
    • Examples: Prednisone, Prednisolone, Methylprednisolone.
    • Mechanism of Action: Similar to inhaled corticosteroids, but with more potent and widespread anti-inflammatory effects.
    • Clinical Uses: Used for short courses (e.g., 5-10 days) to treat acute asthma exacerbations. Occasionally used for long-term control in patients with severe, persistent asthma that is not controlled with other medications.
    • Side effects: Long term use can cause serious side effects.
• Leukotriene Modifiers:
  • Examples: Montelukast, Zafirlukast, Zileuton.
  • Mechanism of Action: Block the effects of leukotrienes, which are inflammatory mediators involved in asthma. Montelukast and zafirlukast are leukotriene receptor antagonists (LTRAs), while zileuton inhibits leukotriene synthesis.
  • Clinical Uses: Long-term control medication, particularly in patients with mild to moderate persistent asthma. Can be used as an alternative to ICS or as add-on therapy. Also helpful in patients with aspirin-sensitive asthma.
  • Side Effects: Generally well-tolerated. Rare reports of liver problems with zafirlukast and zileuton.
• Mast Cell Stabilizers:
  • Examples: Cromolyn sodium, Nedocromil.
  • Mechanism of Action: Prevent the release of inflammatory mediators (e.g., histamine) from mast cells.
  • Clinical Uses: Long-term control medication, but less effective than ICS. May be used in children or in patients with mild asthma.
  • Side effects: Throat irritation.
• Anti-IgE Monoclonal Antibody:
  • Examples: Omalizumab.
  • Mechanism of Action: Binds to immunoglobulin E (IgE), an antibody involved in allergic reactions. This prevents IgE from binding to mast cells and triggering the release of inflammatory mediators.
  • Clinical Uses: Used for moderate to severe persistent asthma that is not well-controlled with other medications, particularly in patients with allergic asthma.
  • Side effects: Anaphylaxis (rare).
  • Administration: Subcutaneous injection.
• Anti-Interleukin 5 (IL-5): Mepolizumab, Reslizumab and Benralizumab.
• Anti-Interleukin 4 (IL-4): Dupilumab.

Combination Therapy

Many patients with asthma require a combination of medications to achieve optimal control. Common combinations include:

• SABA (for quick relief) + ICS (for long-term control)
• ICS + LABA (in a single inhaler)
• ICS + LABA + LAMA

The choice of medications depends on the severity of asthma, the frequency of symptoms, and individual patient factors.

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